intel/tools: Handle strides better when dumping buffers

intel/tools: Handle strides better when dumping buffers

The old code would only break at stride boundaries if the stride was
less than 32B; otherwise it would just break every 32B.  This commit
makes it break at stride boundaries and 32B boundaries (starting from
the last stride).  This makes reading large vertex buffers in aubinator
much nicer.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3642>